Separation test of toluene and water

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Recently, some customers have inquired about the separation testing of toluene and water. I’ll share my thoughts. There is generally an emulsion layer between toluene and water. An emulsified layer is present in many sedimentation stratification processes. The emulsion layer is essentially in a chaotic state, making it difficult to ensure repeatability and consistency. If quality of the product is a concern, the emulsion layer should be classified as the aqueous layer. If for the purpose of yield, the emulsion layer should be classified as the toluene layer. Since the thickness of the emulsion layer is not great (if it were too thick, the issue would lie in the overall manufacturing process), there is little sense in recovering the emulsion layer separately. Moreover, because the emulsion layer is quite viscous, managing it independently is troublesome. Based on our company’s STU01 liquid layer separation detection switch, I would like to share some usage experiences. First scenario: If, for product quality reasons, the emulsion layer is removed along with the water in the lower layer, then the upper medium (toluene) should be used as the background. When the instrument outputs 5 or 6 mA, it indicates the lower layer of liquid (water, emulsion layer) ； When the instrument outputs 4mA, it indicates the upper layer liquid (toluene). Second scenario: For the sake of yield, the emulsion layer is removed together with the upper layer of toluene; in that case, the lower layer of medium (water) should be used as the background. When the instrument outputs 4 mA, it indicates the lower layer of medium; when it outputs 5 or 6 mA, it indicates the upper layer of medium. In the third case, the emulsion layer is divided into two halves. To accomplish this step, it is first necessary to understand the components and distribution of the emulsion layer. Next, let’s discuss the issue of the installation location of the instruments. The installation location of the instrument must meet two conditions: 1. The sensor must be completely submerged in the liquid, with no bubbles present in the liquid. 2. The distance between the instrument and the tank valve should be appropriate. Assuming that the time it takes for the liquid to flow through this distance is t1, the instrument’s response time is t2, and the valve’s response time is t3, it must be true that t1 > t2 + t3. The controller adds a delay t4, so that t1 + t4 = t2 + t3.